DE 10 2006 035 744 discloses a device for automatically tensioning a chain of a chain saw. The device has a helical spring which is supported with one end on the housing and with a second end on an adjusting cam. In order to replace the chain, a separate latching cam has to be actuated, in order to relieve the saw chain.
GB 2 481 038 A discloses a tensioning device for a chain, in which tensioning device a latching device is provided which holds the tensioning spring in a stressed state when the sprocket wheel cover is removed.